1. Field of Invention
The invention will provide a space efficient alphanumeric input device that can be used in applications where there is a limited amount of space available for an input device such as desktop telephones, cell phones, personal digital assistances, sprinkler system controls, and medical equipment.
2. Discussion of Prior Art
Since the time telephone numbers have become of standard use, telephone dials had been made with numerals. With the increasingly important role played by the telephone in commerce, groups of alphabets have been assigned to the numeric keys to offer a more convenient way of memorizing a business telephone number, such as in 1-800-FLOWERS.
With the convergence of voice and data, another trend that became popular in recent years was text messaging and data storage, most commonly on mobile phones. The emergence of telephones incorporating a graphical user interface (GUI) has also called for a need for GUI input devices.
While the demand for additional functionality has increased, the ideal space available for an input device on a telephone unit has remained relatively unchanged. Uncompromising as it is, the limitation is a result of the inherent requirement for a practical size that can be handled with ease, especially on mobile phones.
Various inventions have been brought about in an attempt to improve the input capability of telephones and electronic devices alike where space limitation is a barrier.
Some inventions have employed an extra alphanumeric keyboard with a layout similar to the “QWERTY” typewriter keyboards, some side by side with the standard 12-key telephone keypad, while others provide an external unit, which can be hooked up to the telephone. The major drawback of this approach is its bulkiness.
Another invention brought forward is a cluster key arrangement where the members of a group of characters designated to a given primary numeric button are assigned to the secondary buttons, which are smaller buttons attached to the edge of the primary numeric button. This approach clearly suffers from the miniaturized secondary buttons.
Yet, another approach, which is mostly found on some desktop phones and personal digital assistances, is a miniature keyboard with a layout similar to the full sized keyboard found on personal computers. This approach also suffers from the miniaturization of the keys, since they can only be so small, before it becomes impractical to use.
The most common method of adding character input capability to a standard 12-key telephone keypad is to assign three additional characters to the numeric keys such as “A,” “B,” and “C” on the number “2” key. The disadvantage of this approach is the need to repeatedly press the key to input characters. For example, the number “2” key has to be pressed two times to enter character “B” and three times to enter “C.” If it was pressed three times by mistake to enter character “B,” the character has to be deleted and the whole sequence has to be repeated again. Not only that, if two consecutive characters are assigned on the same key, the user has to wait until the system recognizes the current character as the desired character for input, before using the same key to enter the next character.
Two of the most challenging aspects of designing an alphanumeric keypad for a telephone, especially a mobile unit, are efficient use of the limited space, and convenience. The inventions that have been brought forward so far are designed around concepts that suffer from one or more factors of being bulky, miniaturized, or inconvenient.